Abstract:

An apparatus for retrieving music that matches with a user preference
across a plurality of music is provided. The apparatus comprises a
feature vector generating device for generating feature vectors of each
of the music, a clustering device for clustering the music into a
plurality of clusters according to the feature vectors, a music
extraction device for extracting a predetermined number of music from
each of the clusters, a music selection accepting device for accepting a
selection of music by the user from the music, and a music retrieval
device for calculating similarities between a feature vector of the
selected music and feature vectors of each of the music, and retrieving
music that have higher similarities to the selected music among the
music.

Claims:

1. An apparatus for retrieving for music that matches with a preference of
a user across a plurality of music, comprising:a feature vector
generating device for generating feature vectors of said respective
plurality of music;a clustering device for clustering said plurality of
music into a plurality of clusters according to the feature vectors
generated by said feature vector generating device;a music extract device
for extracting a predetermined number of music from each of said
plurality of clusters;a music selection accepting device for accepting a
selection of music by the user from the music extracted by said music
extraction device; anda music retrieval device for calculating
similarities between a feature vector of the music selected, the
selection of which is accepted by said music selection accepting device
and feature vectors of said respective plurality of music, and retrieving
music that have higher similarities to said selected music among said
plurality of music.

2. The apparatus for retrieving music according to claim 1, further
comprising a music playing device for playing the music extracted by said
music extraction device.

3. The apparatus for retrieving music according to claim 1, further
comprising a music purchase accepting device for accepting a purchase of
music made by the user from the music retrieved by said music retrieval
device.

4. The apparatus for retrieving music according to claim 3, further
comprising a reward point providing device for providing a predetermined
number of reward point to at least one of the music selected, the
selection of which is accepted by said music selection accepting device
and the music, the purchase of which is accepted by said music purchase
accepting device.

5. The apparatus for retrieving music according to claim 1, further
comprising a repeating device for repeating the extracting music by said
music extraction device, the accepting a selection of music by said music
selection accepting device, and the retrieving music by said music
retrieval device,wherein said music extraction device:extracts the
predetermined number of music from each of said plurality of clusters
before the music are retrieved by said music retrieval device,
andextracts from the music that are retrieved after the music are
retrieved by said music retrieval device.

6. A method of retrieving music that matches with a preference of a user
across a plurality of music, comprising:a first step of generating
feature vectors of said respective plurality of music;a second step of
clustering said plurality of music into a plurality of clusters according
to the feature vectors generated in the first step;a third step of
extracting a predetermined number of music from each of said plurality of
clusters;a fourth step of accepting a selection of music by the user from
the music extracted in the third step; anda fifth step of calculating
similarities between a feature vector of the music selected, the
selection of which is accepted in the fourth step and feature vectors of
said respective plurality of music, and retrieving music that have higher
similarities to said selected music among said plurality of music.

7. The method of retrieving music according to claim 6, further comprising
a sixth step of playing the music extracted by said music extraction
device.

8. The method of retrieving music according to claim 6, further comprising
a seventh step of accepting a purchase of music made by the user from the
music retrieved in the fifth step.

9. The method of retrieving music according claim 8, further comprising an
eighth step of providing a reward point to at least one of the music
selected, the selection of which is accepted in the fourth step or the
music, the purchase of which is accepted in the seventh step.

10. The method of retrieving music according to claim 6, further
comprising a ninth step of repeating said third step, said fourth step,
and said fifth step,in said third step:the predetermined number of music
is extracted from each of said plurality of clusters before the fifth
step is executed, andthe extraction is executed from the music that are
retrieved after the fifth step is executed.

11. A program for making a computer to execute a method of retrieving
music that matches with a preference of a user across a plurality of
music, comprising:a first step of generating feature vectors of said
respective plurality of music;a second step of clustering said plurality
of music into a plurality of clusters according to the feature vectors
generated in the first step;a third step of extracting a predetermined
number of music from each of said plurality of clusters;a fourth step of
accepting a selection of music by the user from the music extracted in
the third step; anda fifth step of calculating similarities between a
feature vector of the music selected, the selection of which is accepted
in the fourth step and feature vectors of said respective plurality of
music, and retrieving music that have higher similarities to said
selected music among said plurality of music.

Description:

TECHNICAL FIELD

[0001]The present invention relates to an apparatus for music retrieval, a
method of music retrieval, and a program for music retrieval.

BACKGROUND ART

[0002]Until now, various techniques for music retrieval have been proposed
for retrieving music that match with user preferences across a plurality
of music. For example, Patent Literature 1 proposes a technique for music
retrieval which utilizes feeling vectors representing a user's impression
on music and the related feature vector representing the musical
characteristics of that music. Patent Literature 2 proposes another
technique for music retrieval using impression features that quantify
user's impressions on music. Patent Literature 3 proposes a technique for
music retrieval that employs preference information indicating a user's
preference for any given music, feature quantities of that music, and how
many times the music has been played.

[0003]Patent Literature 4 proposes a technique for music retrieval that
employs music parameters that quantify features of music as one or more
factors. Patent Literature 5 proposes a technique for music retrieval
utilizing feature quantities of the frequency spectrum of music. Patent
Literature 6 proposes a technique for music retrieval using numerical
values that represent user's subjective requirements on music. Patent
Literature 7 proposes a technique for music retrieval utilizing user
profiles that represent musical preferences of a user.

SUMMARY OF INVENTION

Technical Problem

[0004]However, with regard to conventional techniques for music retrieval
as those described above, a user must be fully aware of titles,
impressions, and the preference of music the user wishes to retrieve for
before commencing any retrieval. The need therefore exists for an ability
to retrieve music that match with the user preference even when the user
is not fully aware of titles, impressions, and the like of music the user
wishes to retrieve.

[0005]The present invention was conceived in light of the above-described
problems, and an object thereof is to provide an apparatus for music
retrieval, a method of music retrieval, and a program for music retrieval
that are able to retrieve music that match with the user preference even
when the user is not fully aware of which music should be retrieved.

Solution to Problem

[0006]In order to solve above-described problems, the present invention
proposes the followings aspect:

[0007]A first aspect of the present invention proposes an apparatus for
retrieving music that matches with a preference of a user across a
plurality of music (which, for example, corresponds to a music retrieval
apparatus 10 shown in FIG. 2), comprising: a feature vector generating
device for generating feature vectors of said respective plurality of
music (which, for example, corresponds to a feature vector generating
section 101 shown in FIG. 2); a clustering device for clustering said
plurality of music into a plurality of clusters according to the feature
vectors generated by said feature vector generating device (which, for
example, corresponds to a clustering section 102 shown in FIG. 2); a
music extraction device for extracting a predetermined number of music
from each of said plurality of clusters (which, for example, corresponds
to a music extraction section 103 shown in FIG. 2); a music selection
accepting device for accepting a selection of music by the user from the
music extracted by said music extraction device (which, for example,
corresponds to a music selection accepting section 104 shown in FIG. 2);
and a music retrieval device for calculating similarities between a
feature vector of the music selected, the selection of which is accepted
by said music selection accepting device and feature vectors of said
respective plurality of music, and retrieving music that have higher
similarities to said selected music among said plurality of music (which,
for example, corresponds to a music retrieval section 105 shown in FIG.
2).

[0008]According to this invention, the apparatus for retrieving music
generates, by the feature vector generating device, feature vectors for
each of the plurality of music, and clusters, by the clustering device,
the plurality of music into a plurality of clusters according to the
feature vectors generated by feature vector generating device. Then, a
predetermined number of music is extracted from each of the plurality of
clusters by the music extraction device, and a selection of music by the
user from the music extracted by the music extraction device is accepted
by the music selection accepting device. Furthermore, by the music
retrieval device, similarities between a feature vector of the music
selected, the selection of which is accepted by the music selection
accepting device and feature vectors for each of the plurality of music
are calculated, and music that have higher similarities to the selected
music are retrieved among the plurality of music.

[0009]In other words, the plurality of music are clustered into a
plurality of clusters according to their feature vectors, the
predetermined number of music are extracted from each cluster, and the
user is prompted to select music from the music that are extracted. Then,
music having feature vectors having higher similarities to the feature
vector of the music selected by the user are retrieved.

[0010]Accordingly, notwithstanding whether the user is fully aware of
which music should be retrieved or not, by selecting music from the music
that are extracted, the user can retrieve music having higher
similarities to the selected music. Thus, even when the user is not fully
aware of which music should be retrieved, he or she can make a music
retrieval.

[0011]In addition, since the user selects music from the music extracted
from various different clusters, the user can choose music to be used for
a retrieval from a wide variety of music independent of exiting genres.
Thus, music that match with the user preference can be identified.
Furthermore, since titles of music, names of artists, names of genres, or
the like to be retrieved are not required when retrieving, the user can
retrieve titles or artists that the user does not know, or can make a
retrieval from unexpected genres.

[0012]As described above, even when the user is not fully aware of which
music should be retrieved, music that match with the user preference can
be retrieved.

[0013]A second aspect of the present invention proposes the apparatus for
retrieving music according to the first aspect, further comprising a
music playing device for playing the music extracted by said music
extraction device (which, for example, corresponds to a music play
section 106 shown in FIG. 2).

[0014]According to this invention, the apparatus for retrieving music
plays, by the music playing device, the music extracted by the music
extraction device. Thus, since the user can select music after listing to
it, he or she can find music that further matches with his or her
preference.

[0015]A third aspect of the present invention proposes the apparatus for
retrieving music according to the first aspect, further comprising a
music purchase accepting device for accepting a purchase of music made by
the user from the music retrieved by said music retrieval device (which,
for example, corresponds to a music purchase accepting section 107 shown
in FIG. 2).

[0016]According to this invention, the apparatus for retrieving music
accepts, by the music purchase accepting device, a purchase of music made
by the user from the music retrieved by said music retrieval device.
Thus, when music that matches with the user's own preference is
identified, the user can purchase that music.

[0017]A fourth aspect of the present invention proposes the apparatus for
retrieving music according to the third aspect, further comprising a
reward point providing device for providing a predetermined number of
reward point to at least one of the music selected, the selection of
which is accepted by said music selection accepting device and the music,
the purchase of which is accepted by said music purchase accepting device
(which, for example, corresponds to a reward point providing section 108
shown in FIG. 2).

[0018]According to this invention, the apparatus for retrieving music
provides, by the reward point providing device, reward points to at least
one of the music selected, the selection of which is accepted by said
music selection accepting device and the music, the purchase of which is
accepted by said music purchase accepting device.

[0019]Accordingly, providing reward points to the providers of the music
can motivate them to provide more music. This allows music that match
with the user preference to be retrieved from a greater number of music.

[0020]Furthermore, by extracting a predetermined number of music according
to the descending order of the reward point from each cluster when
extracting music by the music extraction device, the user can make a
retrieval based on music that have been frequently purchased or selected.
This enables the user to effectively make a retrieval based on music that
have been frequently selected or purchased, i.e., music which the user is
more interested in.

[0021]Here, music that gather higher reward points in the user's
selections or purchases of music are expected to be music which the user
is more interested in, e.g., well-known music or music offered by famous
artists, as described above. It is also expected that older music that
are not popular at present but were in the past attracts a greater number
of the users' selections of music accepted by music selection accepting
device. Thus, as described above, by extracting a predetermined number of
music according to the descending order of the reward point from each
cluster when extracting music by the music extraction device, effective
retrieval can be achieved. In addition, this may create new need for
music retrieval as means for retrieving older music or music that the
user have already purchased.

[0022]A fifth aspect of the present invention proposes the apparatus for
retrieving music according the first aspect, further comprising a
repeating device for repeating the extraction of music by said music
extraction device, the accepting a selection of music by said music
selection accepting device, and the retrieving music by said music
retrieval device (which, for example, corresponds to a repeating section
109 shown in FIG. 2), wherein said music extraction device extracts the
predetermined number of music from each of said plurality of clusters
before the music are retrieved by said music retrieval device, and
extracts from the music that are retrieved after the music are retrieved
by said music retrieval device.

[0023]According to this invention, the apparatus for retrieving music
repeats, by the repeating device, the extracting music by the music
extraction device, the accepting a selection of music by the music
selection accepting device, and the retrieving music by the music
retrieval device. Furthermore, the music extraction device extracts a
predetermined number of music from each of the plurality of clusters
before the music are retrieved by the music retrieval device, and
extracts from the music that are retrieved according to the descending
order of the similarity after the music are retrieved by the music
retrieval device.

[0024]Accordingly, by repeating extraction of music recursively, accepting
a selection of music, and retrieving music, music retrieval based on the
music selected by the user can be performed several times. As a result,
user can retrieve music that match with the user preference one after
another. Furthermore, when the retrieval results seem to start diverting
from the user preference, a retrieval can be restarted from the beginning
by recreating the music list.

[0025]A sixth aspect of the present invention proposes a method of
retrieving music that matches with a preference of a user across a
plurality of music, comprising: a first step of generating feature
vectors of said respective plurality of music (which, for example,
corresponds to Step 51 shown in FIG. 3); a second step of clustering said
plurality of music into a plurality of clusters according to the feature
vectors generated in the first step (which, for example, corresponds to
Step S2 shown in FIG. 3); a third step of extracting a predetermined
number of music from each of said plurality of clusters (which, for
example, corresponds to Step 11 shown in FIG. 4); a fourth step of
accepting a selection of music by the user from the music extracted in
the third step (which, for example, corresponds to Step S19 shown in FIG.
5); and a fifth step of calculating similarities between a feature vector
of the music selected, the selection of which is accepted in the fourth
step and feature vectors of said respective plurality of music, and
retrieving music that have higher similarities to said selected music
among said plurality of music (which, for example, corresponds to Step
S21 shown in FIG. 5).

[0026]According to this invention, feature vectors for each of the
plurality of music is generated, and the plurality of music are clustered
into a plurality of clusters based on these generated feature vectors.
Then, a predetermined number of music is extracted from each of the
plurality of clusters, and music selected by the user from the music that
are extraction is accepted. Furthermore, similarities between a feature
vector of the music selected, the selection of which is accepted and the
feature vectors for each of the plurality of music are calculated, and
music that have higher similarities to the selected music are retrieved
among the plurality of music.

[0027]In other words, the plurality of music are clustered into a
plurality of clusters according to their feature vectors, the
predetermined number of music are extracted from each cluster, and the
user is prompted to select music from the music that are extracted. Then,
music having feature vectors having higher similarities to the feature
vector of the music selected by the user are retrieved.

[0028]Accordingly, notwithstanding whether the user is fully aware of
which music should be retrieved or not, by selecting music from the music
that are extracted, the user can retrieve music having higher
similarities to the selected music. Thus, even when the user is not fully
aware of which music should be retrieved, he or she can make a music
retrieval.

[0029]In addition, since the user selects music from the music extracted
from various different clusters, the user can choose music to be used for
a retrieval from a wide variety of music independent of exiting genres.
Thus, music that match with the user preference can be identified.
Furthermore, since titles of music, names of artists, names of genres, or
the like to be retrieved are not required when retrieving, the user can
retrieve for titles or artists that the user does not know, or can make a
retrieval from unexpected genres.

[0030]As described above, even when the user is not fully aware of which
music should be retrieved, music that match with the user preference can
be retrieved.

[0031]A seventh aspect of the present invention proposes the method of
retrieving music according to the sixth aspect, further comprising a
sixth step of playing the music in the third step (which, for example,
corresponds to Step S14 shown in FIG. 4).

[0032]According to this invention, the extracted music are played. Thus,
since the user can select music after listing to it, he or she can find
music that further matches with his or her preference.

[0033]An eighth aspect of the present invention proposes the method of
retrieving music according to the sixth aspect, further comprising a
seventh step of accepting a purchase of music made by the user from the
music retrieved in the fifth step (which, for example, corresponds to
Step S15 shown in FIG. 4).

[0034]According to this invention, a purchase of music made by the user
from the music retrieved is accepted. Thus, when music that matches with
the user's own preference is identified, the user can purchase that
music.

[0035]A ninth aspect of the present invention proposes the apparatus for
retrieving music according to the eighth aspect, further comprising an
eighth step of providing a reward point to at least one of the music
selected, the selection of which is accepted in the fourth step or the
music, the purchase of which is accepted in the seventh step (which, for
example, correspond to Step S17 shown in FIG. 4 and Step S20 shown in
FIG. 5).

[0036]According to this invention, a reward point is provided to at least
one of the music selected, the selection of which is accepted and the
music, the purchase of which is accepted.

[0037]Accordingly, providing reward points to the providers of the music
can motivate them to provide more music. This allows music that match
with the user preference to be retrieved from a greater number of music.

[0038]Furthermore, by extracting a predetermined number of music according
to the descending order of the reward point from each cluster when
extracting music, the user can make a retrieval based on music that have
been frequently purchased or selected. This enables the user to
effectively make a retrieval based on music that have been frequently
selected or purchased, i.e., music which the user is more interested in.

[0039]Here, music that gather higher reward points in the user's
selections or purchases of music are expected to be music which the user
is more interested in, e.g., well-known music or music offered by famous
artists, as described above. It is also expected that older music that
are not popular at present but were in the past attracts a greater number
of the users' selections of music accepted by music selection accepting
device. Thus, as described above, by extracting a predetermined number of
music according to the descending order of the reward point from each
cluster when extracting music by the music extraction device, effective
retrieval can be achieved. In addition, this may create new need for
music retrieval as means for retrieving older music or music that the
user have already purchased.

[0040]A tenth aspect of the present invention proposes the method of
retrieving music according to sixth aspect, further comprising a ninth
step of repeating said third step, said fourth step, and said fifth step
(which, for example, corresponds to transitioning the flow from Step S21
or S22 shown in FIG. 5 to Step 11 shown in FIG. 4, or transitioning the
flow from Step S22 shown in FIG. 5 to Step 13 shown in FIG. 4), wherein
in said third step, the predetermined number of music is extracted from
each of said plurality of clusters before the fifth step is executed, and
the extraction is executed from the music that are retrieved after the
fifth step is executed.

[0041]According to this invention, the extracting music, the accepting a
selection of music, and the retrieving music are repeated. Furthermore,
the predetermined number of music is extracted from each of the plurality
of clusters before the music are retrieved, and music are extracted from
the music that are retrieved according to the descending order of the
similarity after the music are retrieved.

[0042]Accordingly, by repeating extraction of music recursively, accepting
a selection of music, and retrieving music, music retrieval based on the
music selected by the user can be performed several times. As a result,
user can retrieve music that match with the user preference one after
another. Furthermore, when the retrieval results seem to start diverting
from the user preference, a retrieval can be restarted from the beginning
by recreating the music list.

[0043]A eleventh aspect of the present invention proposes a program for
making a computer to execute a method of retrieving music that matches
with a preference of a user across a plurality of music, comprising: a
first step of generating feature vectors of said respective plurality of
music (which, for example, corresponds to Step 51 shown in FIG. 3); a
second step of clustering said plurality of music into a plurality of
clusters according to the feature vectors generated in the first step
(which, for example, corresponds to Step S2 shown in FIG. 3); a third
step of extracting a predetermined number of music from each of said
plurality of clusters (which, for example, corresponds to Step 11 shown
in FIG. 4); a fourth step of accepting a selection of music by the user
from the music extracted in the third step (which, for example,
corresponds to Step S19 shown in FIG. 5); and a fifth step of calculating
similarities between a feature vector of the music selected, the
selection of which is accepted in the fourth step and feature vectors of
said respective plurality of music, and retrieving music that have higher
similarities to said selected music among said plurality of music (which,
for example, corresponds to Step S21 shown in FIG. 5).

[0044]According to this invention, by making the computer to execute the
method of retrieving music, feature vectors for each of the plurality of
music is generated, and the plurality of music are clustered into a
plurality of clusters based on these generated feature vectors. Then, a
predetermined number of music is extracted from each of the plurality of
clusters, and music selected by the user from the music that are
extracted is accepted. Furthermore, similarities between a feature vector
of the music selected, the selection of which is accepted and the feature
vectors for each of the plurality of music are calculated, and music that
have higher similarities to the selected music are retrieved among the
plurality of music.

[0045]In other words, the plurality of music are clustered into a
plurality of clusters according to their feature vectors, the
predetermined number of music are extracted from each cluster, and the
user is prompted to select music from the music that are extracted. Then,
music having feature vectors having higher similarities to the feature
vector of the music selected by the user are retrieved.

[0046]Accordingly, notwithstanding whether the user is fully aware of
which music should be retrieved or not, by selecting music from the music
that are extracted, the user can retrieve music having higher
similarities to the selected music. Thus, even when the user is not fully
aware of which music should be retrieved, he or she can make a music
retrieval.

[0047]In addition, since the user selects music from the music extracted
from various different clusters, the user can choose music to be used for
a retrieval from a wide variety of music independent of exiting genres.
Thus, music that match with the user preference can be identified.
Furthermore, since titles of music, names of artists, names of genres, or
the like to be retrieved are not required when retrieving, the user can
retrieve titles or artists that the user does not know, or can make a
retrieval from unexpected genres.

[0048]As described above, even when the user is not fully aware of which
music should be retrieved, music that match with the user preference can
be retrieved.

Advantageous Effects of Invention

[0049]According to this invention, notwithstanding whether the user is
fully aware of which music should be retrieved or not, by selecting music
from the music that are extracted, the user can retrieve for music having
higher similarities to the selected music. Thus, even when the user is
not fully aware of which music should be retrieved, he or she can make a
music retrieval.

[0050]In addition, since the user selects music from the music extracted
from various different clusters, the user can choose music to be used for
a retrieval from a wide variety of music independent of exiting genres.
Thus, music that match with the user preference can be identified.
Furthermore, since titles of music, names of artists, names of genres, or
the like to be retrieved are not required when retrieving, the user can
retrieve titles or artists that the user does not know, or can make a
retrieval from unexpected genres.

[0051]As described above, even when the user is not fully aware of which
music should be retrieved, music that match with the user preference can
be retrieved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0052]FIG. 1 is a diagram illustrating a structure of a music retrieving
system according to an embodiment of the present invention;

[0053]FIG. 2 is a block diagram illustrating a structure of a music
retrieval apparatus according to an embodiment of the present invention;

[0054]FIG. 3 is a diagram illustrating a main processing of the music
retrieval apparatus according to an embodiment of the present invention;

[0055]FIG. 4 is a diagram illustrating a music retrieval processing of the
music retrieval apparatus according to an embodiment of the present
invention;

[0056]FIG. 5 is a diagram illustrating the music retrieval processing of
the music retrieval apparatus according to an embodiment of the present
invention;

[0057]FIG. 6 is a diagram illustrating an example of a display screen on a
terminal according to an embodiment of the present invention; and

[0058]FIG. 7 is a diagram illustrating an example of the display screen on
the terminal according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

[0059]Hereinafter, an embodiment of the prevent invention will be
described with reference to the drawings.

[0060]It should be noted that components of these embodiments may be
replaced with any existing components where necessary, or wide variety of
variations including combinations with other existing components are also
contemplated. Accordingly, the description of this embodiment should not
be interpreted as limiting the contents of the invention that are defined
in the appended claims.

Structure of Music Retrieving System

[0061]FIG. 1 is a diagram illustrating a structure of a music retrieval
system 1 according to an embodiment of the present invention. The music
retrieval system 1 includes a music storage device 20 having a plurality
of music stored therein, a music retrieval apparatus 10 that retrieves
music that match with a preference of a user across the plurality of
music stored in the music storage device 20, and a terminal 70 that is
provided to be operable by the user. The music storage device 20 is
communicatively coupled to the music retrieval apparatus, and the music
retrieval apparatus 10 is communicatively coupled to the terminal 70 via
the Internet 50.

[0062]It should be noted that although only one terminal 70 is shown in
FIG. 1 as a terminal being communicatively coupled and being operable by
the user, a plurality of terminals may be coupled in addition to the
terminal 70. Hereinafter, a case wherein the user having the terminal 70
retrieves music that match with the user preference through the music
retrieval apparatus 10.

Structure of Music Retrieval Apparatus

[0063]FIG. 2 is a block diagram illustrating the structure of the music
retrieval apparatus 10. The music retrieval apparatus 10 includes a
feature vector generating section 101 that generates feature vectors for
the respective music stored in the music storage device 20; a clustering
section 102 that clusters each of the music stored in the music storage
device 20 into a plurality of clusters; a music extraction section 103
that extracts music from the plurality of music stored in the music
storage device 20; a music selection accepting section 104 that accepts a
selection of music made by the user; a music retrieval section 105 that
retrieves music; a music play section 106 that plays the music extracted
by the music extraction section 103; a music purchase accepting section
107 that accepts a purchase of the music made by the user; a reward point
providing section 108 that provides a reward point to the music selected,
the selection of which is made by the music selection accepting section
104; and a repeating section 109 that repeats extraction of music by the
music extraction section 103, accepting a selection of music by the music
selection accepting section 104, and retrieves music by the music
retrieval section 105.

[0064]The feature vector generating section 101 extracts features from
each of the music stored in the music storage device 20, and generates
feature vectors for the respective music. It should be noted that this
embodiment employs the Tree-based Vector Quantization technique (TreeQ)
disclosed in Japanese Unexamined Patent Application, First Publication
No. 2006-243887 as a technique for generating feature vectors for each
music.

[0065]The clustering section 102 clusters each of the music stored in the
music storage device 20 into a plurality of clusters based on a feature
vector of each music which is generated by the feature vector generating
section 101. It should be noted that this embodiment employs the k-means
clustering algorithm as a clustering technique. It also should be noted
that in order to reduce the processing time, it is desirable to sample
some parts of music for generating clusters since the processing time
required for clustering all music into clusters increases as the number
of music stored in the music storage device 20 increases.

[0066]The music extraction section 103 extracts 20 music from the
plurality of music stored in the music storage device 20. More
specifically, the music extraction section 103 extracts a piece of music
based on the resultant clusters made by the clustering section 102 when a
"Retrieve Again" button B4 is operated which will be described below, or
before the music retrieval section 105 retrieves music, i.e., when
extraction of music is executed for the first time. After music are
retrieved by the music retrieval section 105, i.e., when extraction of
music are executed out twice or more, the music extraction section 103
extracts the music that have been retrieved by the music retrieval
section 105.

[0067]The music selection accepting section 104 accepts a selection of
music made by the user from the music extracted by the music extraction
section 103. More specifically, details of each of the 20 pieces of music
extracted by the music extraction section 103, such as the names or the
authors, are sent to the terminal 70, and the details are displayed on a
display screen of the terminal 70. This prompts the user having the
terminal 70 to select a piece of music from the 20 pieces of music
extracted by the music extraction section 103. Once a piece of music is
selected by the user from the music extracted by the music extraction
section 103, an information indicating the music selected by the user is
received from the terminal 70.

[0068]The music retrieval section 105 retrieves 20 pieces of music that
have higher similarities to the music received by the music selection
accepting section 104. More specifically, the music retrieval section 105
calculates similarities between the feature vector of the selected music
selection accepted by the music selection accepting section 104 and
feature vectors of the respective plurality of music stored in the music
storage device 20, and identifies music having similarities to the
feature vector of the selected music equal to or greater than a
predetermined value from the plurality of music stored in the music
storage device 20.

[0069]It should be noted that this embodiment employs the cosine
similarity as the technique to calculate similarities. For example, the
similarity Sim (dk1, dk2) between the feature vector of the selected
music dk1 and a feature vector dk2 of one of the plurality of music
stored in the music storage device 20 can be expressed as follows:

[0070]The music play section 106 plays a part of music which is selected
by the user for playing it in a play mode from the 20 pieces of music
extracted by the music extraction section 103. More specifically, once
the user executes an operation on the terminal 70 to play a piece of
music in the play mode while the music selection accepting section 104
displays details of the 20 pieces of music extracted by the music
extraction section 103, the selected music is read from the music storage
device 20. Then, a part of the music that is read is sent to the terminal
70, and is output from speaker(s) of the terminal 70.

[0071]The music purchase accepting section 107 accepts a purchase of music
made by the user from the music retrieved by the music retrieval section
105. More specifically, once the user executes an operation on the
terminal 70 to purchase a piece of music while the music selection
accepting section 104 displays details of the 20 pieces of music
extracted by the music extraction section 103, a billing processing is
started. After the billing processing is completed and the user finishes
the payment of the charge, the music which the user wishes to purchase is
read from the music extraction section 103 and is sent to the terminal
70.

[0072]The reward point providing section 108 provides one reward point for
each of the music selected, the selection of which is accepted by the
music selection accepting section 104 and the music, the purchase of
which is accepted by the music purchase accepting section 107. For
example, an administrator of the music retrieval system 1 calculates the
sum of reward points provided to each music for a predetermined period of
time, and gives money according to the calculated reward points to a
music provider.

[0073]The repeating section 109 repeats extraction of music recursively by
the music extraction section 103, accepting a selection of music by the
music selection accepting section 104, and retrieving music by the music
retrieval section 105 until a purchase of music is accepted by the music
purchase accepting section 107 or the user execute an operation on the
terminal 9 to terminate the retrieval of music by the music retrieval
apparatus 10.

Music Retrieval Processing by the Apparatus for Music Retrieval

[0074]The procedure executed by the music retrieval apparatus 10 for
retrieving music that match with a user preference across the plurality
of music stored in the music storage device 20 will be described with
reference to the flowcharts of FIGS. 3-5.

[0075]First, the main processing executed by the music retrieval apparatus
10 will be described with reference to the flowchart of FIG. 3.

[0076]First, in Step 51, the feature vector generating section 101
generates feature vectors for the respective music stored in the music
storage device 20.

[0077]Then, in Step S2, the clustering section 102 clusters the music
stored in the music storage device 20 into a plurality of clusters
according to the feature vectors of the respective music generated in
Step 51.

[0078]Then, in Step S3, it is determined whether the user executes an
operation to start a music retrieval. If it is determined that the user
executes an operation to start a music retrieval, the flow proceeds to
Step S4. Otherwise, if it is determined that the user does not make an
operation to start a music retrieval, Step S3 is repeated.

[0079]Once the user executes an operation to start a music retrieval, the
terminal 70 sends a retrieval started signal to the music retrieval
apparatus 10. The music retrieval apparatus 10 determines whether the
user executes an operation to start a music retrieval based on reception
of a retrieval started signal from the terminal 70.

[0080]Then, in Step S4, a music retrieval processing shown in the
flowcharts of FIGS. 4 and 5 is executed and the flow returns to Step S3.

[0081]Next, the music retrieval processing executed by the music retrieval
apparatus 10 will be described with reference to the flowcharts of FIGS.
4 and 5.

[0082]First, in Step S11, the music extraction section 103 extracts 20
pieces of music from the plurality of music stored in the music storage
device 20. More specifically, when Step S11 is executed after Step S3 in
FIG. 3 or when Step S11 is executed after Step S22 in FIG. 5, 20 pieces
of music are extracted, each of which being selected from each cluster
according to the results of Step S2 in FIG. 2. On the other hand, when
Step S11 is executed after Step S21 in FIG. 5, 20 pieces of music
retrieved in Step S21 are extracted.

[0083]Then, in Step S12, the music selection accepting section 104 sends
details of the 20 pieces of music extracted in Step S11 to the terminal
70, and the details are displayed on a display screen of the terminal 70,
as shown in FIGS. 6 and 7. The details of the music include "Music IDs"
that are unique numerical values for identifying the respective plurality
of music stored in the music storage device 20, "Titles" indicating the
titles of the music, and "Artists" indicating the authors of the music.
In addition to those details of the music, the following buttons are
displayed for each of the music: "Play" button B1 for the user to operate
when playing the music in the play mode, "Purchase" button B2 for the
user to operate when purchasing the music, and "Retrieve" button B3 for
the user to operate when retrieving music. Also displayed is one
"Retrieve Again" button B4 for the user to operate when restarting music
retrieval from the beginning. Noted that FIGS. 6 and 7 will be described
in detail later.

[0084]Then, in Step S13, the music play section 106 determines whether the
user operates a "Play" button B1. If it is determined that the user
operates a "Play" button B1, the flow proceeds to Step S14. Otherwise, if
it is determined that the user does not operate a "Play" button B1, the
flow proceeds to Step S15.

[0085]Once the user operates a "Play" button B1, the terminal 70 sends a
play requested signal indicating which music corresponds to the operated
"Play" button B1 to the music retrieval apparatus 10. The music retrieval
apparatus 10 determines whether the user operates a "Play" button B1
based on reception of a play started signal from the terminal 70.

[0086]Then, in Step S14, the music play section 106 plays a part of the
music corresponding to the operated "Play" button B1 among the 20 pieces
of music extracted in Step S11. More specifically, the music
corresponding to the operated "Play" button B1 is read from the music
storage device 20 based on the play requested signal, and a part of that
music is sent to the terminal 70 and is output from the speaker(s) of the
terminal 70.

[0087]Then, in Step S15, the music purchase accepting section 107
determines whether the user operates a "Purchase" button B2. If it is
determined that the user operates a "Purchase" button B2, the flow
proceeds to Step S16. Otherwise, if it is determined that the user does
not operate a "Purchase" button B2, the flow proceeds to Step S18 in FIG.
5.

[0088]Once the user operates a "Purchase" button B2, the terminal 70 sends
a purchase requested signal indicating which music corresponds to the
operated "Purchase" button B2 to the music retrieval apparatus 10. The
music retrieval apparatus 10 determines whether the user operates a
"Purchase" button B2 based on reception of a purchase requested signal
from the terminal 70.

[0089]Then, in Step S16, the music purchase accepting section 107 sells
the music corresponding to the operated "Purchase" button B2 among the 20
pieces of music extracted in Step S11. More specifically, a billing
processing for the music corresponding to the operated "Purchase" button
B2 is started based on the purchase requested signal. After the billing
processing is completed and the user finishes the payment of the charge,
the music corresponding to the operated "Purchase" button B2 is read from
the music storage device 20 and is sent to the terminal 70. When the
transmission of the music to the terminal 70 is completed, the flow
proceeds to Step S17.

[0090]Then, in Step S17, the reward point providing section 108 provides
one reward point to the music corresponding to the operated "Purchase"
button B2. The music retrieval processing is then completed, and the flow
proceeds to Step S3 in FIG. 3.

[0091]Then, in Step S18 shown in FIG. 5, it is determined whether the user
executes an operation to terminate music retrieval. If it is determined
that the user executes an operation to terminate music retrieval, the
music retrieval processing is terminated and the flow proceeds to Step S3
in FIG. 3. If it is determined that the user does not make an operation
to terminate music retrieval, the flow proceeds to Step S19.

[0092]Once the user executes an operation to terminate music retrieval,
the terminal 70 sends a retrieval terminated signal to the music
retrieval apparatus 10. The music retrieval apparatus 10 determines
whether the user executes an operation to terminate music retrieval based
on reception of a retrieval terminated signal from the terminal 70.

[0093]Then, in Step S19, the music selection accepting section 104
determines whether the user operates a "Retrieve" button B3. If it is
determined that the user operates a "Retrieve" button B3, the flow
proceeds to Step S20. Otherwise, if it is determined that the user does
not operate a "Retrieve" button B3, the flow proceeds to Step S22.

[0094]Once the user operates a "Retrieve" button B3, the terminal 70 sends
a retrieval requested signal indicating which music corresponds to the
operated "Retrieve" button B3 to the music retrieval apparatus 10. The
music retrieval apparatus 10 determines whether the user operates a
"Retrieve" button B3 based on reception of a retrieval requested signal
from the terminal 70.

[0095]Then, in Step S20, the reward point providing section 108 provides
one reward point to the music corresponding to the operated "Retrieve"
button B3.

[0096]Then, in Step S21, the music retrieval section 105 retrieves 20
pieces of music having higher similarities to the music corresponding to
the operated "Retrieve" button B3 among the plurality of music stored in
the music storage device 20, and the flow proceeds to Step S11.

[0097]Then, in Step S22, it is determined whether the user operates the
"Retrieve Again" button B4. If it is determined that the user operates
the "Retrieve Again" button B4, the flow proceeds to Step S11. Otherwise,
if it is determined that the user does not operate the "Retrieve Again"
button B4, the flow proceeds to Step S13.

[0098]Once the user operates the "Retrieve Again" buttons B4, a retrieval
again requested signal indicating the operation of this button is sent to
the music retrieval apparatus 10. The music retrieval apparatus 10
determines whether the user operates the "Retrieve Again" buttons B4
based on reception of a retrieval again requested signal from the
terminal 70.

Exemplary Screen of Details of Music on Music Retrieval Apparatus

[0099]Examples of details of music displayed by the music retrieval
apparatus 10 will be described with reference to FIGS. 6 and 7.

[0100]FIG. 6 shows an example of the display screen on the terminal 70
when the above-described Step S11 is executed after Step S3. In this
exemplary screen, details of totaling 20 pieces of music, each of which
being extracted from each cluster, are displayed.

[0101]FIG. 7 shows an example of the display screen on the terminal 70
when the above-described Step S11 is executed after Step S21. This
exemplary screen is displayed when the user operates a "Retrieve" button
B3 corresponding to the music having the Music ID of "10593." In this
example, details of totaling 20 pieces of music, namely, the music having
the Music ID of "10593" and 19 pieces of music having higher similarities
to this music are displayed

[0102]According to the music retrieval apparatus 10 described above, the
plurality of music stored in the music storage device 20 are clustered
into a plurality of clusters according to their feature vectors, totaling
20 pieces of music are extracted, each of which being extracted from each
cluster, and the user is prompted to select a piece of music from the 20
pieces of music. Then, 20 pieces of music having feature vectors having
higher similarities to the feature vector of the music selected by the
user are retrieved.

[0103]Accordingly, notwithstanding whether the user is fully aware of
which music should be retrieved or not, by selecting music from the 20
pieces of music that are extracted, the user can retrieve music having
higher similarities to the selected music. Thus, even when the user is
not fully aware of which music should be retrieved, he or she can make a
music retrieval.

[0104]In addition, since the user selects music from the music extracted
from various different clusters, the user can choose music to be used for
a retrieval from a wide variety of music independent of exiting genres.
Thus, music that match with the user preference can be identified.
Furthermore, since titles of music, names of authors, names of genres, or
the like to be retrieved are not required when retrieving, the user can
retrieve names or authors that the user does not know, or can make a
retrieval from unexpected genres.

[0105]As described above, even when the user is not fully aware of which
music should be retrieved, music that match with the user preference can
be retrieved.

[0106]Furthermore, according to the music retrieval apparatus 10 described
above, when the user operates "Play" button B1, a part of music
corresponding to the operated "Play" button B1 is output from the
speaker(s) of the terminal 70. Thus, since the user can select music
after listing to it, he or she can find music that further matches with
his or her preference.

[0107]Furthermore, according to the music retrieval apparatus 10 described
above, when the user operates "Purchase" button B2, the music
corresponding to the operated "Purchase" button B2 is sold to the user.
Thus, when music that matches with the user's own preference is
identified, the user can purchase that music.

[0108]Furthermore, according to the music retrieval apparatus 10 described
above, every time the user operates a "Purchase" button B2 or "Retrieve"
button B3, one reward point is provided to the music corresponding to the
operated "Purchase" button B2 or "Retrieve" button B3.

[0109]Thus, the administrator of the music retrieval system 1 calculates
the sum of reward points provided to each music for a predetermined
period of time, and gives money according to the calculated reward points
to a music provider. Since this motivates music providers to provide more
music, music that match with the user preference can be retrieved from a
greater number of music.

[0110]For example, when 20 pieces of music are extracted by the music
extraction section 103, music may be extracted one by one from each
cluster according to the descending order of the reward point.
Alternatively, or additionally, when retrieving music by the music
retrieval section 105, music may be retrieved according to the descending
order of the reward point, in the case where music have the same
similarity. This enables the user to make a retrieval based on music
corresponding to frequently operated "Purchase" buttons B2 or "Retrieve"
buttons B3, i.e., music that have been frequently purchased or selected.
This enables the user to effectively make a retrieval based on music that
have been frequently purchased or selected, i.e., music which the user is
more interested in.

[0111]Here, music that gather a greater number of operations of "Purchase"
buttons B2 or "Retrieve" buttons B3 are expected to be music which the
user is more interested in, e.g., well-known music or music offered by
famous artists, as described above. It is also expected that older music
that are not popular at present but were in the past attracts a greater
number of operations of "Retrieve" buttons B3. Thus, as described above,
when 20 pieces of music are extracted by the music extraction section
103, music may be extracted one by one from each cluster according to the
descending order of the reward point. Alternatively, or additionally,
when retrieving music by the music retrieval section 105, music may be
retrieved according to the descending order of the reward point, in the
case where music have the same similarity. This enables effective
retrieval. In addition, this may create new need for music retrieval as
means for retrieving older music or music that the user have already
purchased.

[0112]Furthermore, when a plurality of terminals that are operable by
users are communicatively coupled to the music retrieval apparatus 10,
reward points of the respective terminals are summed. As described above,
when 20 pieces of music are extracted by the music extraction section
103, music may be extracted one by one from each cluster according to the
descending order of the reward point. Alternatively, or additionally,
when retrieving music by the music retrieval section 105, music may be
retrieved according to the descending order of the reward point, in the
case where music have the same similarity. This makes possible to
retrieve music that are popular among all users, i.e., bestseller music,
having higher similarities.

[0113]Furthermore, according to the music retrieval apparatus 10 described
above, extraction of music, accepting operations of "Retrieve" buttons
B3, and retrieving music are repeated recursively until the user operates
a "Purchase" button B2 or the user executes an operation to terminate
music retrieval.

[0114]Accordingly, by repeating extraction of music recursively, accepting
operations of "Retrieve" button B3, and retrieving music, music retrieval
based on the music selected by the user can be performed several times.
As a result, user can retrieve music that match with the user preference
one after another.

[0115]Furthermore, according to the music retrieval apparatus 10 described
above, when the user operates the "Retrieve Again" button B4, 20 pieces
of music in total are extracted again, each of which being extracted from
each cluster, and the user are prompted to make a selection from these
music. This enables the user to command the music retrieval apparatus 10
to re-execute music retrieval once again with a simple operation of using
the "Retrieve Again" button B4 when retrieved music diverts from the
user's taste, or when the user wishes to retrieve music that have
different tastes or are in different genres.

[0116]It should be noted that the present invention may be embodied by
storing the processing executed by the music retrieval apparatus 10 of
the present invention in a computer readable recording media, and
commanding the music retrieval apparatus 10 to load and execute the
programs stored in these recording media.

[0117]Furthermore, the above-described programs may be transmitted from
the music retrieval apparatus 10 having the programs stored therein to
other computer systems, through a transmission medium, or through carrier
wave carried on a transmission medium. As used herein, the term
"transmission medium" that propagates programs refers to a medium that is
capable of transmitting information, including networks (communication
networks), such as the Internet, or communication lines, such as
telephone lines (communication path).

[0118]Furthermore, the above-described programs may implement some part of
the functions described above. In addition, such programs may implement
the above-described functions in a combination with programs stored in
the music retrieval apparatus 10, that is, the programs may be so-called
differential files (differential programs).

[0119]Although some embodiments of the present invention have been
described with reference to the attached drawings, this invention is not
limited to the embodiments described above. Variants thereof can be
envisaged which do not exceed the scope of the present invention.

[0120]For example, although the above-described embodiment employs the
Tree-based Vector Quantization technique (TreeQ) disclosed in Japanese
Unexamined Patent Application, First Publication No. 2006-243887 as a
technique for generating feature vectors for each music, the k-means
clustering algorithm as a clustering technique, and the cosine similarity
as the technique to calculate similarities, these are not intended to be
limiting.

[0121]Although the above-described embodiment also employs feature vectors
of music for music retrieval, this is not intended to be limiting.

[0122]Furthermore, in the above-described embodiment, although the number
of music users can select is one, this is not intended to be limiting and
users may select more than a piece of music.